Robotic devices have been proposed for performing a working operation, such as cleaning or polishing surfaces, that are not accessible to normal manual operations. In general, the robotic devices have been used on flat or planer surfaces such as windows, building panels and the like. The typical robotic device includes a pair of endless belts or tracks, each carrying a series of vacuum cups. The belts are independently and remotely driven to move the device across the surface to be treated, and a source of vacuum, such as a vacuum pump, is connected to the vacuum cups to create a negative pressure within the cups so that the cups can grip the surface and enable the robotic device to move over inclined or vertical surfaces. A typical robotic device can operate on smooth continuous surfaces but if the device moves across an obstruction or crack in a vertical or inclined surface, the vacuum may be lost, resulting in the device falling from the surface.
Large commercial aircraft are normally washed and waxed every thirty days. Because of the large size and shape of the aircraft it is customary to erect a scaffold along side the aircraft and a number of workers supported on the scaffold then hand scrub the outer surface of the aircraft. After scrubbing, the aircraft is waxed and polished using manual rotary buffers. The buffers are relatively heavy and due to the large surface area of the aircraft a buffing operation is a tedious and time consuming operation. The entire operation of scrubbing, waxing and buffing the aircraft usually takes a period of 20 to 30 hours utilizing 10 workers.
Commercial aircraft are also subjected to a non-destructive inspection after 7,000 cycles of pressurization. Each take-off and landing in which the aircraft is pressurized is considered to be a pressurization cycle. In the typical non-destructive inspection, the paint is stripped entirely from the aircraft and the seams and rivets are manually inspected. If a defect is observed during the inspection, the area of the defect is marked and is subjected to an eddy-current sensor to determine the magnitude of the defect. After the manual inspection the aircraft is repainted and subsequently waxed and buffed.
The normal paint stripping, inspecting, repainting and waxing operation is extremely time-consuming and labor intensive, resulting in a substantial expenditure. As a further problem the paint stripping operation presents a serious environmental problem, in that methylene chloride is generally used as the solvent to remove the paint and for a large aircraft, such as a Boeing 747, upwards of 1,000 gallons of methylene chloride may be required to strip the paint from the aircraft. As methylene chloride is toxic and presents an environmental problem, pollution abatement equipment is necessary in order to remove the solvent fumes from the paint stripping area.